JP2007145312A - Automatic brake control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic brake control device capable of automatically controlling braking in a truck and a bus. <P>SOLUTION: A stepwise brake control is automatically performed when TTC obtained according to a relative distance and a relative speed between an object and one's own vehicle is lower than a predetermined value. This stepwise brake control is provided for gradually increasing brake force or a brake reduction speed over a plurality of stages in time series. A rate of change in expected brake force from a rising point of the brake force or the brake reduction speed of the respective stages or the brake force in a section up to reaching the brake reduction speed or the brake reduction speed, is set at a predetermined value. Or a changing process of the brake force of the respective stages or the expected brake force from the rising point of the brake reduction speed or the brake force in the section up to reaching the brake reduction speed or the brake reduction speed, is set for a changing process of running along a curved shape defined by a predetermined function. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is used for large vehicles (trucks, buses) for transporting cargo and passengers.

  The electronic control of automobiles has progressed steadily, and events that have so far depended solely on the judgment of the driver have been carried out by onboard computers.

  As an example, the distance between the preceding vehicle and the host vehicle (inter-vehicle distance) is monitored by a radar, and when the inter-vehicle distance approaches abnormally, appropriate braking control is automatically performed to prevent a collision. Sometimes, there is an automatic braking control device that minimizes the damage (see, for example, Patent Document 1).

JP 2005-31967 A

  The above-described automatic braking control device has already been put into practical use in passenger cars, but it must be solved when trying to use the same function for large vehicles (trucks, buses) for transporting cargo and passengers. There is a problem that must be done.

  In other words, large vehicles have an extremely large mass compared to passenger cars, and in addition to the driver's own safety, passenger and cargo safety must be ensured, and it seems that this is done by automatic braking control of passenger cars. It is difficult to achieve the intended purpose with simple simple braking control, and it is necessary to perform more advanced automatic braking control than in the case of passenger cars. However, since such means has not been established, automatic braking control devices for trucks and buses have not yet been put into practical use.

  The present invention has been made under such a background, and an object thereof is to provide an automatic braking control device that can realize automatic braking control in a truck or a bus.

  The automatic braking control device of the present invention is a device that can reduce the impact at the time of a collision while maintaining the stability of a large vehicle such as a truck or a bus by performing stepwise braking control.

  In the present invention, when performing stepwise braking control, a change in braking force or braking deceleration in a section from the rising point of the braking force or braking deceleration in each step until the intended braking force or braking deceleration is reached. The rate of change of the braking force or braking deceleration in the section from the rising point of the braking force or braking deceleration at each stage to the arrival of the desired braking force or braking deceleration It is characterized by a change process along a curve shape defined by a function. Thereby, it is possible to avoid sudden braking and maintain the stability of the vehicle.

  That is, the present invention includes a control unit that automatically performs a braking control based on a sensor output including a distance from an object in the traveling direction of the host vehicle without a driving operation. When the predicted value of the time required for the object and the vehicle, which are derived based on the relative distance and relative speed between the object and the vehicle obtained, to fall below a predetermined distance, falls below a set value Stepwise braking control means for automatically performing stepwise braking control is provided, and the stepwise braking control means includes braking control means for gradually increasing the braking force or braking deceleration over a plurality of stages in time series. A braking control device.

  The predicted value of the time required for the object and the vehicle to be less than a predetermined distance derived based on the relative distance and relative speed between the object and the vehicle is, for example, the object and the vehicle Is a predicted value of the time required for the collision (hereinafter referred to as TTC (Time To Collision)).

  Here, a feature of the present invention is that the stepwise braking control means is configured such that the stepwise braking control means has a braking force in a section from the rising point of the braking force or braking deceleration of each step to the intended braking force or braking deceleration. Alternatively, a means for setting the rate of change in braking deceleration to a predetermined value is provided.

  Alternatively, the stepwise braking control means may perform a predetermined process of changing the braking force or braking deceleration in a section from the rising point of the braking force or braking deceleration of each step until reaching the desired braking force or braking deceleration. There is a means to change the curve shape defined by the function. Thereby, the change of braking force or braking deceleration can be made smoother than the former.

  According to the present invention, automatic braking control in a truck or bus can be realized.

(First Example)
The automatic braking control device of the first embodiment will be described with reference to FIGS. FIG. 1 is a control system configuration diagram of the first embodiment. FIG. 2 is a flowchart showing a control procedure of a braking control ECU (Electric Control Unit) of the first embodiment. FIG. 3 is a diagram showing a braking pattern at the time of idle loading that the braking control ECU has. FIG. 4 is a diagram for explaining the braking force change rate in the braking pattern. FIG. 5 is a diagram showing a braking pattern at the time of half product of the braking control ECU. FIG. 6 is a diagram showing a braking pattern at the time of fixed volume possessed by the braking control ECU. FIG. 7 is a diagram showing a full-scale braking pattern that the braking control ECU has.

  As shown in FIG. 1, the braking control ECU 4, the gateway ECU 5, the meter ECU 6, the engine ECU 8, the axle weight meter 9, and the EBS (Electric Breaking System) _ECU 10 are connected to each other via a VehicleCAN (J1939) 7.

  Further, the steering sensor 2, the yaw rate sensor 3, and the vehicle speed sensor 13 are connected to the VehicleCAN (J1939) 7 via the gateway ECU 5, and the sensor information is taken into the braking control ECU 4. The brake control is performed by the EBS_ECU 10 driving the brake actuator 11. Note that the brake instruction to the EBS_ECU 10 is performed by the brake operation and braking control ECU 4 at the driver's seat (not shown). The brake information including information on the brake operation by the driver is also output from the EBS_ECU 10 and taken into the brake control ECU 4. The engine ECU 8 performs fuel injection amount control of the engine 12 and other engine control. Note that the injection amount control instruction to the engine ECU 8 is performed by the accelerator operation of the driver's seat. Further, the alarm display and sound output by the braking control ECU 4 are displayed on the display unit (not shown) of the driver's seat by the meter ECU 6. Since the control system related to steering other than the steering sensor 2 is not directly related to the present invention, the illustration is omitted.

  In the first embodiment, as shown in FIG. 1, a millimeter wave radar 1 for measuring a distance from a preceding vehicle or an object such as a falling object in the traveling direction of the own vehicle, and a steering sensor 2 for detecting a steering angle. The brake control ECU 4 includes a brake control ECU 4 that automatically performs a brake control based on sensor outputs such as a yaw rate sensor 3 for detecting the yaw rate and a vehicle speed sensor 13 for detecting the vehicle speed. When the TTC derived based on the relative distance and relative speed between the object and the vehicle obtained from the sensor outputs from the millimeter wave radar 1 and the vehicle speed sensor 13 falls below a set value, it is automatically stepped. Stepwise braking control means for performing braking control is provided. This stepwise braking control means, as shown in FIG. 3, is a braking control means for gradually increasing the braking force over three stages in time series. Including the.

  In the example of FIG. 3B, first, braking of about 0.1 G is applied from TTC 2.4 seconds to 1.6 seconds in the first stage marked “alarm”. At this stage, the so-called sudden braking is not yet applied, and the stop lamp is lit to notify the following vehicle that the sudden braking will be performed. Next, in the second stage described as “enlarged area braking”, braking of about 0.3 G is applied from TTC 1.6 seconds to 0.8 seconds. Finally, in the third stage, marked as “full-scale braking”, the maximum braking (about 0.5G) is applied from TTC 0.8 seconds to 0 seconds.

  Further, when the driver performs a strong braking operation exceeding the braking force shown above, the stronger braking force is given priority. However, the braking operation of the driver acts as a brake instruction to the EBS_ECU 10, and the EBS_ECU 10 appropriately adjusts the braking force of the brake actuator 11 even if the driver should perform an excessive braking operation.

  In the following description, the preceding vehicle will be described, but the automatic braking control device of this embodiment is also effective for falling objects on the road.

  As shown in FIGS. 3, 5, and 6, the braking control ECU 4 includes a braking pattern selection unit 40 that changes the braking pattern according to the weight of the loaded cargo or the passenger. As a method of changing, the braking pattern storage unit 41 of the braking control ECU 4 stores in advance a plurality of control patterns for “empty product”, “half product”, and “constant product”, and the braking pattern selection unit 40. Can be realized by selecting a braking pattern that matches (or approximates) these braking patterns according to the weight. The weight information of the loaded cargo and passengers is obtained by the axle weight meter 9 shown in FIG. 1 and is taken into the braking control ECU 4.

  Here, the feature of the present embodiment is that the braking control ECU 4 starts from the starting point of the braking force at each stage “alarm”, “enlarged area braking”, and “full-scale braking” as shown in FIG. There is provided means for setting a change rate of the braking force in a section until the braking force is reached to a predetermined value.

In FIG. 4, the braking force change rate is described using the automatic braking control pattern at the time of the idle product in FIG. 3B as an example. The notation of 2.4 seconds, 1.6 seconds, and 0.8 seconds in FIGS. 3 and 4 is TTC. TTC is
Distance between vehicles / (Self-vehicle speed-preceding vehicle speed)
Is calculated by In the example of FIGS. 3B and 4, the “alarm” phase is started from the time point when the TTC is 2.4 seconds. Further, the “enlarged area braking” stage is started from the time point when the TTC is 1.6 seconds. Further, the “full-scale braking” stage is started from the time point when the TTC is 0.8 seconds.

In the present embodiment, as shown in FIG. 4, in a section from the rising point (2.4 seconds, 1.6 seconds, 0.8 seconds) of each stage until the desired braking force is reached,
Rate of change α = b (G) / a (seconds)
To increase the braking force. For the rate of change α, an appropriate value is obtained in advance by a test run or simulation so that the rate of change of the braking force is within the allowable range where the change in the posture of the vehicle does not become unstable when braking is started at each stage. To set. Since specific numerical values vary depending on the type of vehicle such as a bus or truck, no illustration is given. In FIG. 5 (half product) or FIG. 6 (constant product), the same value is used as the change rate α at each stage.

  In addition, when the host vehicle speed is less than 60 km / h and the steering angle is not less than +30 degrees or not more than −30 degrees, there is provided means for prohibiting activation of the stepwise braking control means. A yaw rate may be used instead of the steering angle.

  In other words, the stepwise braking control performed by the automatic braking control device of this embodiment is such that the host vehicle speed before starting the braking control is 60 km / h or more, and a large steering wheel operation such as when changing lanes or driving sharp curves is performed. Since it is assumed that the vehicle is not used, it is possible to limit the start of the stepwise braking control in other driving conditions.

  Also, if the vehicle speed before the start of braking control is less than 60 km / h, the vehicle has less kinetic energy, so there is no problem even if simple sudden braking control as conventionally applied to passenger cars is performed. Since the usefulness of performing stepwise braking control is low, the activation of stepwise braking control is limited. Further, if the steering angle before starting the braking control is +30 degrees or more or −30 degrees or less, this is during lane change or sharp curve traveling, so it is outside the staged braking control application event and staged braking control. Restrict startup of. In this case, a yaw rate may be used instead of the steering angle.

  In this embodiment, when the host vehicle speed before the start of braking control is less than 60 km / h and is 15 km / h (minimum speed at which the usefulness of automatic braking control (full-scale braking control) is recognized) or more, stepwise Although the braking control is not performed, as shown in FIG. 7, only the full-scale braking control shown in FIGS. 3B, 5B, and 6B is performed. When only such full-scale braking control is performed, braking control equivalent to conventional automatic braking control used in passenger cars can be applied. Note that when applying such automatic braking control equivalent to the conventional one, there is no need to determine whether or not the vehicle is changing lanes or traveling sharply.

  Next, the operation of the automatic braking control device of this embodiment will be described with reference to the flowchart of FIG. FIG. 2 will be described with reference to an example of a braking pattern at the time of idle product (FIG. 3), but the procedure of the flowchart of FIG. 2 is also applied at the time of half product (FIG. 5) or constant product (FIG. 6). As shown in FIG. 2, the distance between the preceding vehicle and the vehicle speed of the preceding vehicle are measured and monitored by the millimeter wave radar 1. Further, the vehicle speed is measured by the vehicle speed sensor 13 and monitored. Further, the weight of the loaded cargo and passengers is measured and monitored by the axle weight meter 9 (S1). The braking pattern selection unit 40 of the braking control ECU 4 selects in advance one of the braking patterns (FIGS. 3, 5, and 6) based on the measurement result of the weight. The following description is an example in which the braking pattern of FIG. 3 is selected.

TTC is calculated from the inter-vehicle distance, the own vehicle speed, and the vehicle speed of the preceding vehicle (S2). The calculation method is
Distance between vehicles / (Self-vehicle speed-Vehicle speed of the preceding vehicle)
It is. The vehicle speed before starting the braking control is 60 km / h or more (S3), the steering angle before starting the braking control is +30 degrees or less and -30 degrees or more (S4), and the TTC is shown in FIG. If it is in the area (1) (S5), "alarm" braking control is executed (S8). If the TTC is in the region (2) shown in FIG. 3A (S6), "enlarged region braking" control is executed (S9). If the TTC is in the region (3) shown in FIG. 3 (a) (S7), "full-scale braking" control is executed (S10).

  Further, if the vehicle speed before starting the braking control is less than 60 km / h and 15 km / h or more (S3, S11) and the TTC is in the region (4) shown in FIG. In contrast, the fact that the relative distance from the preceding vehicle is short is notified (S13). Notification is performed by warning display or buzzer sound. Further, if the TTC is in the region (5) shown in FIG. 3C (S14), “full-scale braking” control is executed as shown in FIG. 7 (S10).

  Note that the yaw rate from the yaw rate sensor 3 can be used instead of the steering angle from the steering sensor 2. Alternatively, the steering angle and the yaw rate may be used in combination.

  Here, FIG. 3, FIG. 5 and FIG. 6 will be described. The straight lines c, f, and i in FIGS. 3, 5, and 6 are called steering avoidance limit straight lines. Further, curves B, D, and F in FIGS. 3, 5, and 6 are called braking avoidance limit curves.

  That is, the steering avoidance limit straight line is a straight line indicating a limit at which a collision can be avoided by a steering operation within a predetermined TTC in the relationship between one relative distance to the obstacle and one relative speed with the obstacle. The braking avoidance limit curve is a curve indicating a limit at which a collision can be avoided by a braking operation within a predetermined TTC in the relationship between one relative distance to the obstacle and one relative speed with the obstacle.

  3, 5, and 6, in the area under both of these straight lines or curves, the collision can no longer be avoided by the steering operation or the braking operation.

  For example, in the example of the empty product in FIG. 3, the straight line c has TTC set to 0.8 seconds. In this embodiment, a straight line a when the TTC is 2.4 seconds is provided above the steering avoidance limit straight line c, and a straight line b when the TTC is 1.6 seconds is provided. Further, a curve A with TTC set at 1.6 seconds is provided above the braking avoidance limit curve B with TTC set at 0.8 seconds.

  The initial state of the vehicle has a relative distance and a relative speed with respect to the obstacle indicated by a black point G in FIG. When the host vehicle speed before the start of braking control is 60 km / h or more, the relative distance gradually decreases, and when the vehicle reaches the position of the straight line a, the alarm mode is set (area (1)). In the alarm mode, braking of about 0.1 G is applied from TTC 2.4 seconds to 1.6 seconds. During this period, it is meaningful to turn on the stop lamp and inform the subsequent vehicle of braking. When the relative speed further decreases and reaches the position of the straight line b, the expansion area braking mode is set (area (2)). In the enlarged area braking mode, braking of about 0.3 G is applied from TTC 1.6 seconds to 0.8 seconds. When the position of the straight line c is reached, the full braking mode is set (area (3)). In the full-scale braking mode, the maximum braking (about 0.5G) is applied from TTC 0.8 seconds to 0 seconds. According to the calculation in step S2 of FIG. 2, a collision occurs at this time. However, in practice, since the host vehicle speed is reduced by the braking control, the actual TTC is longer than the calculation result of step S2.

  In other words, in the calculation of TTC in the automatic braking control device targeted by the present invention, precise distance measurement and complicated calculation processing are omitted as much as possible, and a general-purpose simple distance measurement device (for example, millimeter wave radar) or a calculation device is used. It is assumed that. Such considerations are useful for keeping vehicle manufacturing costs or maintenance costs low.

  Therefore, strictly speaking, the preceding vehicle and the subject vehicle, which are the objects, are performing a uniform acceleration motion by braking (deceleration), and therefore the TTC calculation must also be calculated based on the uniform acceleration motion. By calculating the TTC as simply performing constant velocity motion, precise distance measurement and complicated arithmetic processing are omitted.

  In addition, by performing a calculation that is regarded as such a constant velocity motion, the calculated TTC value becomes smaller than the actual TTC value. There is no hindrance.

  Further, when the host vehicle speed before starting the braking control is 15 km / h or more and less than 60 km / h, the relative distance is gradually shortened, and when the vehicle reaches the position of the straight line b, the notification mode is set (region (4)). . In the notification mode, the driver is notified that the relative distance to the obstacle is shortened by an alarm display or a buzzer sound. When the position of the straight line c is reached, the full braking mode is set as shown in FIG. 7 (region (5)). In the full-scale braking mode, the maximum braking (about 0.5G) is applied from TTC 0.8 seconds to 0 seconds.

  FIG. 5 shows an example at half load, and FIG. 6 shows an example at constant load. However, if the equal braking force is compared, the braking distance increases as the weight of the loaded cargo or passenger increases. The avoidance limit straight line and the braking avoidance limit curve also move upward in the figure. Thereby, the area of area | region (1), (2), (3), (4), (5) becomes large according to the weight of a loaded cargo or a passenger.

  The straight lines a to c in FIG. 3 correspond to the straight lines df to f in FIG. 5 and the straight lines g to i in FIG. 6, and the curves A and B in FIG. 3 are the curves C and D in FIG. , F, the black point G in FIG. 3 corresponds to the black point H in FIG. 5 and the black point I in FIG.

(Second embodiment)
A second embodiment will be described with reference to FIG. FIG. 8 is a diagram for explaining a braking force change curve in the braking pattern. In the second embodiment, as shown in FIG. 8, the braking control ECU 4 defines a change process of the braking force in a section from the rising point of the braking force at each stage to the arrival of the desired braking force by a predetermined function. Means for making a changing process along the curve shape is provided.

That is, in the “alarm” region, the braking force changing process is a changing process along the curve shape defined by the function y = f ₀ (x). In the “enlarged region braking” region, the changing process of the braking force is a changing process along the curve shape defined by the function y = f ₁ (x). In the “real braking” region, the changing process of the braking force is a changing process along a curved line defined by the function y = f ₂ (x).

  These functions are simulated for each vehicle type and for each of the unloading, half-loading, and constant-loading modes to replace the linear braking force change in the braking pattern shown in FIG. 4 with a smooth curvilinear braking force change. Alternatively, it is assumed that an optimal function is obtained and determined in advance by test running. FIG. 8 shows a braking pattern at the time of idle product, but a braking pattern is also determined for half product and constant product.

  According to the second embodiment, the braking force change can be made smoother than in the first embodiment.

  ADVANTAGE OF THE INVENTION According to this invention, the automatic braking control in a truck or a bus | bath can be implement | achieved, and it can contribute to traffic safety.

The control system block diagram of a present Example. The flowchart which shows the control procedure of braking control ECU of a present Example. The figure which shows the braking pattern at the time of the idle product which braking control ECU has. The figure for demonstrating the braking force change rate in a braking pattern. The figure which shows the braking pattern at the time of the half product which braking control ECU has. The figure which shows the braking pattern at the time of the fixed volume which braking control ECU has. The figure which shows the full-scale braking pattern which braking control ECU has. The figure for demonstrating the braking force change curve in a braking pattern.

Explanation of symbols

1 Millimeter wave radar 2 Steering sensor 3 Yaw rate sensor 4 Braking control ECU
5 Gateway ECU
6 Meter ECU
7 VehicleCAN (J1939)
8 Engine ECU
9 Shaft weigher 10 EBS_ECU
11 Brake actuator 12 Engine 13 Vehicle speed sensor 40 Brake pattern selection unit 41 Brake pattern storage unit

Claims (2)

Control means for automatically performing braking control without a driving operation based on a sensor output including a distance from an object in the traveling direction of the host vehicle,
The control means predicts the time required for the object and the vehicle, which are derived based on the relative distance and relative speed between the object and the vehicle obtained from the sensor output, to be equal to or less than a predetermined distance. Stepwise braking control means for automatically performing stepwise braking control when the value falls below the set value,
The stepwise braking control means is an automatic braking control device including a braking control means for gradually increasing the braking force over a plurality of stages in time series,
The stepwise braking control means sets a change rate of the braking force or braking deceleration in a section from the rising point of the braking force or braking deceleration of each step to the intended braking force or braking deceleration as a predetermined value. An automatic braking control device characterized by comprising: Control means for automatically performing braking control without a driving operation based on a sensor output including a distance from an object in the traveling direction of the host vehicle,
The control means predicts the time required for the object and the vehicle, which are derived based on the relative distance and relative speed between the object and the vehicle obtained from the sensor output, to be equal to or less than a predetermined distance. Stepwise braking control means for automatically performing stepwise braking control when the value falls below the set value,
The stepwise braking control means is an automatic braking control device including a braking control means for gradually increasing a braking force or a braking deceleration over a plurality of stages in a time series,
The stepwise braking control means is configured to change a braking force or a braking deceleration change process in a section from a rising point of a braking force or a braking deceleration of each step to an intended braking force or braking deceleration according to a predetermined function. An automatic braking control device comprising means for changing along a defined curved shape.

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